The present invention relates, in general, to electronics, and more particularly, to methods of forming semiconductor devices and structure.
In the past, the semiconductor industry utilized various methods and structures to form digital circuits using differential amplifiers. For example differential amplifiers were used to form emitter coupled logic (ECL) circuits such as multiplexers and flip-flops. These differential amplifier circuits typically utilized multiple differential amplifiers that shared the collectors of some of the transistors that were used to form the differential amplifiers. For example, a collector of one transistor of a differential pair could be connected to a collector of an equivalent transistor of another differential pair. Under some operating conditions the first differential pair may be disabled. If a signal were applied to the input of a disabled transistor, a parasitic capacitance of the disabled transistor caused cross-talk that affected the output signal resulting in jitter in the output signal and false triggering of other circuits that were connected to the output.
Accordingly, it is desirable to have a method of reducing crosstalk in circuits that have shared transistors, and reducing jitter in the output signal.
For simplicity and clarity of illustration, elements in the figures are not necessarily to scale, and the same reference numbers in different figures denote the same elements. Additionally, descriptions and details of well-known steps and elements are omitted for simplicity of the description. As used herein current carrying electrode means an element of a device that carries current through the device such as a source or a drain of an MOS transistor or an emitter or a collector of a bipolar transistor or a cathode or anode of a diode, and a control electrode means an element of the device that controls current through the device such as a gate of an MOS transistor or a base of a bipolar transistor. Although the devices are explained herein as certain NPN transistors, a person of ordinary skill in the art will appreciate that complementary devices are also possible in accordance with the present invention.